A dual-differential analog charge-coupled device for time-shared recursive filters

AMONG THE EARLIEST proposed applications of charge-transfer devices1 was a digitally-controlled analog recursive filter in monolithic form. Subsequently , a second-order recursive filter using a bucket brigade device was reported. Later, using the differential mode of operation for charge transfer devices3, a programmable bandpass filter and tone generator was described. Third-order recursive filters using bucket brigades4 and chargecoupled devices` have also been reported. This approach to filtering must show significantly higher cost effectiveness to compete successfully against the entrenched technologies.